NASHVILLE (AP) — The Tennessee Agriculture Department is advising soybean and cotton farmers to follow new federal guidelines when applying a weed killer blamed for drifting and damaging crops in neighboring fields.

In a news release, the department says dicamba should only be applied by certified applicators. The guidelines also list times the herbicide can be applied and buffers that must be observed.

In eleven Tennessee counties , additional buffers are required to protect threatened or endangered species. And dicamba cannot be sprayed at all in Wilson County.

In addition to the rules, University of Tennessee weed specialists recommend not spraying dicamba when the temperature is above 85 degrees.

The department also urges beekeepers and farmers growing sensitive crops to register with FieldWatch. Applicators are required to check the directory at www.fieldwatch.com before spraying.